[PATCH v4] x3daudio: fix lib exports

[Rafał Mużyło]

x3daudio: fix lib exports

1. in case of x3daudio1_{0,1,2}, two exported functions are for some
reason decorated (though only on 32bit)
2. tests show these functions should be stdcall, not cdecl; more
exactly, header for 1.1 shows that too (1.7 header shows that changed at
some point)

Signed-off-by: Rafał Mużyło <galtgendo(a)o2.pl>